1. Field of the Invention
The present invention relates to a separating apparatus for separating a composite substrate into a first substrate and a second substrate previously bonded to each other.
2. Description of the Related Art
In an optical device fabrication process, a light emitting layer is formed through a buffer layer on the front side of a substantially disk-shaped epitaxy substrate such as a sapphire substrate and a silicon carbide substrate, wherein the light emitting layer is composed of an n-type semiconductor layer and a p-type semiconductor layer from gallium nitride (GaN), indium gallium phosphide (InGaP), or aluminum gallium nitride (AlGaN). The light emitting layer is partitioned into a plurality of regions by a plurality of crossing streets, and a plurality of optical devices such as light emitting diodes and laser diodes are respectively formed in the plural regions, thus obtaining an optical device wafer. The optical device wafer is divided along the streets to manufacture the individual optical devices.
As a technique for improving the luminance of an optical device, a manufacturing method called lift-off is disclosed in JP-T-2005-516415. This method includes the steps of bonding a transfer substrate of molybdenum (Mo), copper (Cu), silicon (Si), etc. through a bonding metal layer of gold tin (AuSn) etc. to a light emitting layer composed of an n-type semiconductor layer and a p-type semiconductor layer, wherein the light emitting layer is formed through a buffer layer on the front side of an epitaxy substrate of sapphire, silicon carbide, etc. constituting an optical device wafer, next applying a laser beam having an absorption wavelength (e.g., 248 nm) to the buffer layer from the back side of the epitaxy substrate to thereby break the buffer layer, and next separating the epitaxy substrate from the light emitting layer, thereby transferring the light emitting layer to the transfer substrate.